The structure of the tungsten atom. Chemical properties of tungsten. Characteristics and applications of tungsten. Being in nature

Tungsten is a chemical element of Mendeleev's periodic table that belongs to Group VI. Tungsten occurs naturally as a mixture of five isotopes. In its usual form and under normal conditions, it is a solid silver-gray metal. It is also the most refractory of all metals.

Basic properties of tungsten

Tungsten is a metal with remarkable physical and chemical properties. Tungsten is used in almost all branches of modern production. Its formula is usually expressed in the form of a metal oxide designation - WO 3. Tungsten is considered the most refractory metal. It is assumed that only seaborgium can be even more refractory. But this cannot be said for sure, since the seaborgium has a very short lifetime.

This metal has special physical and chemical properties. Tungsten has a density of 19300 kg / m 3, its melting point is 3410 ° C. According to this parameter, it ranks second after carbon - graphite or diamond. Tungsten occurs naturally in the form of five stable isotopes. Their mass numbers are in the range from 180 to 186. Tungsten has a 6th valence, and in compounds it can be 0, 2, 3, 4 and 5. The metal also has a fairly high level of thermal conductivity. For tungsten, this figure is 163 W / (m * deg). By this property, it even exceeds such compounds as aluminum alloys. The mass of tungsten is due to its density, which is equal to 19 kg / m 3. The oxidation state of tungsten ranges from +2 to +6. In the highest degrees of its oxidation, the metal has acidic properties, and in the lowest - basic.

In this case, alloys of lower tungsten compounds are considered unstable. The most resistant are compounds with a degree of +6. They also exhibit chemical properties most characteristic of a metal. Tungsten tends to form complexes easily. But metallic tungsten is usually very resistant. It begins to interact with oxygen only at a temperature of +400 ° C. The crystal lattice of tungsten belongs to the type of cubic body-centered.

Interaction with other chemicals

If tungsten is mixed with dry fluorine, you can get a compound called "hexafluoride", which melts at 2.5 ° C, and boils at 19.5 ° C. A similar substance is obtained by combining tungsten with chlorine. But for such a reaction, a sufficiently high temperature is required - about 600 ° C. However, the substance easily resists the destructive effect of water and practically does not undergo changes in the cold. Tungsten is a metal that does not dissolve in alkalis without oxygen. However, it dissolves easily in a mixture of HNO 3 and HF. The most important of the chemical compounds of tungsten are its trioxide WO 3, H 2 WO 4 - tungstic acid, as well as its derivatives - tungstate salts.

You can consider some of the chemical properties of tungsten with the reaction equations. For example, the formula WO 3 + 3H 2 \u003d W + 3H 2 O. In it, the tungsten metal is reduced from oxide, its property of interaction with hydrogen is manifested. This equation reflects the process of obtaining tungsten from its trioxide. The following formula denotes such a property as the practical insolubility of tungsten in acids: W + 2HNO3 + 6HF \u003d WF6 + 2NO + 4H2O. One of the most notable tungsten-containing substances is carbonyl. Dense and ultra-thin pure tungsten coatings are obtained from it.

Discovery history

Tungsten is a metal that got its name from the Latin language. Translated, this word means "wolf foam". This unusual name comes from the behavior of the metal. Accompanying the mined tin ore, tungsten interfered with the release of tin. Because of it, only slags were formed during the smelting process. It was said about this metal that it "eats tin like a wolf eats a sheep." For many, it is interesting who discovered the chemical element tungsten?

This scientific discovery was made simultaneously in two places by different scientists, independently of each other. In 1781, a Swedish chemist Scheele obtained the so-called "heavy stone" by experimenting with nitric acid and scheelite. In 1783, brothers-chemists from Spain named Eluard also announced the discovery of a new element. More precisely, they discovered tungsten oxide, which was dissolved in ammonia.

Alloys with other metals

Currently, single-phase and multi-phase tungsten alloys are distinguished. They contain one or more extraneous elements. The most famous compound is an alloy of tungsten and molybdenum. The addition of molybdenum gives tungsten its tensile strength. Also, the category of single-phase alloys includes compounds of tungsten with titanium, hafnium, zirconium. Rhenium gives the greatest plasticity to tungsten. However, practically using such an alloy is a rather laborious process, since rhenium is very difficult to obtain.

Since tungsten is one of the most refractory materials, making tungsten alloys is not an easy task. When this metal just begins to boil, others are already turning into a liquid or gas state. But modern scientists know how to obtain alloys using the electrolysis process. Alloys containing tungsten, nickel and cobalt are used to apply a protective layer to fragile materials.

In the modern metallurgical industry, alloys are also obtained using tungsten powder. To create it, special conditions are required, including the creation of a vacuum environment. Due to some peculiarities of the interaction of tungsten with other elements, metallurgists prefer to create alloys not with a two-phase characteristic, but with the use of 3, 4 or more components. These alloys are especially strong, but with strict adherence to formulas. At the slightest deviation in percentage components, the alloy can turn out to be brittle and unusable.

Tungsten - an element used in engineering

Incandescent filaments of ordinary bulbs are made from this metal. And also the tubes for X-ray machines that make up vacuum furnaces that must be used at extremely high temperatures. Steel that contains tungsten has a very high level of strength. Such alloys are used for the manufacture of tools in a wide variety of areas: for well drilling, in medicine, mechanical engineering.

The main advantage of joining steel and tungsten is wear resistance, low probability of damage. The most famous tungsten alloy in construction is called "win". Also, this element is widely used in the chemical industry. With its addition, paints and pigments are created. Tungsten oxide 6 is especially widely used in this area. It is used for the manufacture of tungsten carbides and halides. Another name for this substance is tungsten trioxide. 6 is used as a yellow pigment in paints for ceramics and glassware.

What are heavy alloys?

All tungsten-based alloys that have a high density are called heavy. They are obtained only using powder metallurgy methods. Tungsten is always the basis of heavy alloys, where its content can be up to 98%. In addition to this metal, nickel, copper and iron are added to heavy alloys. However, they can also include chromium, silver, cobalt, molybdenum. The most popular alloys are VMZH (tungsten - nickel - iron) and VNM (tungsten - nickel - copper). The high density of these alloys allows them to absorb hazardous gamma radiation. They are used to make wheel flywheels, electrical contacts, rotors for gyroscopes.

Wolfram carbide

About half of all tungsten is used to make strong metals, especially tungsten carbide, which has a melting point of 2770 ° C. Tungsten carbide is a chemical compound that contains an equal number of carbon and tungsten atoms. This alloy has special chemical properties. Tungsten gives it such strength that it is twice as strong as steel.

Tungsten carbide is widely used in industry. Cutting objects are made from it, which must be very resistant to high temperatures and abrasion. Also made from this element:

• Aircraft parts, car engines.
• Details for spaceships.
• Medical surgical instruments used in the field of abdominal surgery. Such instruments are more expensive than conventional medical steel, but they are more productive.
• Jewelry, especially wedding rings. Such popularity of tungsten is associated with its strength, which for the wedding ceremony symbolizes the strength of the relationship, as well as its appearance. The characteristics of polished tungsten are such that it retains a mirror-like, shiny appearance for a very long time.
• Balls for luxury ballpoint pens.

Wins - Tungsten Alloy

Around the second half of the 1920s, alloys for cutting tools, which were obtained from tungsten carbides and metallic cobalt, began to be produced in many countries. In Germany, this alloy was called vidia, in the States - carbola. In the Soviet Union, such an alloy was called "win". These alloys have proven to be excellent for machining cast iron products. Pobedit is a cermet alloy with an extremely high level of strength. It is produced in the form of plates of various shapes and sizes.

The manufacturing process is reduced to the following: tungsten carbide powder, fine nickel or cobalt powder is taken, and everything is mixed and pressed in special molds. The plates pressed in this way are subjected to further heat treatment. This gives a very hard alloy. These inserts are used not only for cutting cast iron, but also for making drilling tools. Pobedit plates are brazed onto drilling equipment using copper.

The abundance of tungsten in nature

This metal is very rare in the environment. After all the elements, it takes 57th place and is contained in the form of tungsten clarke. The metal also forms minerals - scheelite and wolframite. Tungsten migrates to groundwater either as its own ion or as various compounds. But its highest concentration in groundwater is negligible. It amounts to hundredths of a mg / l and practically does not change their chemical properties. Tungsten can also enter natural water bodies from factories and factories.

Impact on the human body

Tungsten practically does not enter the body with water or food. There may be a risk of inhalation of tungsten particles together with industrial air. However, despite belonging to the category of heavy metals, tungsten is not toxic. Tungsten poisoning occurs only in those associated with tungsten production. Moreover, the degree of influence of metal on the body is different. For example, tungsten powder, tungsten carbide, and a substance such as tungstic acid anhydrite can cause lung damage. Its main symptoms are general malaise, fever. More severe symptoms occur with poisoning with tungsten alloys. This occurs when the alloy dust is inhaled and leads to bronchitis, pneumosclerosis.

Metallic tungsten, getting inside the human body, is not absorbed in the intestines and is gradually excreted. Soluble tungsten compounds can pose a great danger. They are deposited in the spleen, bones, and skin. With prolonged exposure to tungsten compounds, symptoms such as brittle nails, peeling of the skin, and various kinds of dermatitis may occur.

Tungsten reserves in various countries

The largest resources of tungsten are found in Russia, Canada and China. According to scientists' forecasts, about 943 thousand tons of this metal are located in the domestic territories. According to these estimates, the overwhelming majority of the reserves are located in Southern Siberia and the Far East. The share of explored resources is very insignificant - it is only about 7%.

In terms of the number of proven tungsten deposits, Russia is second only to China. Most of them are located in the regions of Kabardino-Balkaria and Buryatia. But in these deposits, not pure tungsten is mined, but its ores, which also contain molybdenum, gold, bismuth, tellurium, scandium and other substances. Two-thirds of the volumes of tungsten obtained from prospected sources are contained in refractory ores, where scheelite is the main tungsten-bearing mineral. The share of easy-dressing ores accounts for only one third of all production. The characteristics of tungsten mined in Russia are lower than abroad. The ores contain a high percentage of tungsten trioxide. There are very few placer metal deposits in Russia. Tungsten sands are also of low quality, with a lot of oxides.

Tungsten in economics

Global tungsten production began its growth around 2009, when the Asian industry began to recover. China remains the largest producer of tungsten. For example, in 2013, this country's production accounted for 81% of the global supply. About 12% of the demand for tungsten is associated with the production of lighting products. According to experts' forecasts, the use of tungsten in this area will decrease against the background of the use of LED and fluorescent lamps both in domestic conditions and in production.

It is believed that the demand for tungsten in the electronics industry is expected to grow. The high wear resistance of tungsten and its ability to withstand electricity makes it the most suitable metal for voltage regulators. However, in terms of volume, this demand is still quite insignificant, and it is believed that by 2018 it will grow by only 2%. However, according to forecasts of scientists, in the near future there should be an increase in demand for cemented carbide. This is due to the growth of automotive production in the USA, China, Europe, as well as the increase in the mining industry. It is believed that by 2018, the demand for tungsten will increase by 3.6%.

One of the most common chemical elements is tungsten. It is designated by the symbol W and has an atomic number of 74. Tungsten belongs to a group of metals with high wear resistance and melting point. In the periodic system of Mendeleev, it is in the 6th group, has similar properties with its "neighbors" - molybdenum, chromium.

Discovery and history

As early as the 16th century, such a mineral as wolframite was known. It was interesting in that when tin was smelted from ore, its foam turned into slag and, of course, this interfered with production. Since then, wolframite has been called "wolf foam" (with it. Wolf Rahm). The name of the mineral passed on to the metal itself.

In 1781, the Swedish chemist Scheele treated scheelite with nitric acid. In the course of the experiment, he got a yellow heavy stone - tungsten oxide (VI). Two years later, the Eluard brothers (Spanish chemists) obtained pure tungsten from the Saxon mineral.

This element and its ores are mined in Portugal, Bolivia, South Korea, Russia, Uzbekistan, and the largest reserves were found in Canada, the USA, Kazakhstan and China. Only 50 tons of this element are mined per year, so it is expensive. Let's take a closer look at what kind of metal is tungsten.

Element properties

As mentioned earlier, tungsten is one of the most refractory metals. It has a brilliant light gray color. Its melting point is 3422 ° C, and its boiling point is 5555 ° C, its density in its pure form is 19.25 g / cm 3, and its hardness is 488 kg / mm². It is one of the heaviest metals and highly corrosion resistant. It is practically insoluble in sulfuric, hydrochloric and hydrofluoric acids, but quickly reacts with hydrogen peroxide. What kind of metal is tungsten if it does not react with molten alkalis? Reacting with sodium hydroxide and oxygen, it forms two compounds - sodium tungstate and ordinary water H 2 O. It is interesting that when the temperature rises, tungsten self-heats up, then the process is much more active.

Tungsten production

When asked which group of metals tungsten belongs to, one can answer that it belongs to the category of rare elements, like rubidium and molybdenum. This, in turn, means that it is characterized by a small scale of production. In addition, such a metal is not obtained by reduction from raw materials; first, it is processed into chemical compounds. How is the rare metal obtained?

1. The required element is isolated from the ore material and concentrated in a solution or sediment.
2. The next step is to obtain a pure chemical compound by purification.
3. From the resulting substance, a pure rare metal is isolated - tungsten.

Gravity, flotation, magnetic or electrostatic separation are used to concentrate ore. The result is a concentrate that contains 55-65% of tungsten anhydride WO 3. To obtain a powder, it is reduced with hydrogen or carbon. For some products, this is where the process of receiving the item ends. Thus, tungsten powder is used to prepare hard alloys.

Manufacturing of sticks

We have already found out what kind of metal is tungsten, and now we will find out in what assortment it is made. The powder compound is used to make compact ingots - bars. For this, only powder is used that has been reduced with hydrogen. They are made by pressing and sintering. The result is quite strong but fragile ingots. In other words, they are difficult to forge. To improve this technological property, the bars are subjected to high temperature processing. A different assortment is made from this product.

Tungsten rods

Of course, this is one of the most common types of products made from this metal. What kind of tungsten is used to make them? These are the bars described above, which are forged on a rotary forging machine. It is important to note that the process takes place in a heated state (1450-1500 ° C). The rods obtained are used in a wide variety of industries. For example, for the manufacture of welding electrodes. In addition, tungsten rods are widely used in heaters. They operate in furnaces at temperatures up to 3000 ° C in vacuum, inert gas or hydrogen. The rods can also be used as cathodes for electronic and gas-discharge devices, radio tubes.

Interestingly, the electrodes themselves are non-consumable, and therefore, during welding, it is necessary to feed the filler material (wire, rod). When melted with the material to be welded, it creates a weld pool. These electrodes are usually used for welding non-ferrous metals.

Tungsten and wire

Here is another common product. Tungsten wire is made from the forged rods we discussed earlier. Drawing is carried out with a gradual decrease in temperature from 1000 ° C to 400 ° C. Then, the product is cleaned by annealing, electrolytic polishing or electrolytic etching. Since tungsten is a refractory metal, the wire is used in resistance elements in heating furnaces at temperatures up to 3000 ° C. It is used for making thermoelectric converters, as well as filament lamp spirals, loop heaters and much more.

Tungsten-carbon compounds

Tungsten carbides are considered very important from a practical point of view. They are used for the manufacture of hard alloys. Compounds with carbon have a positive coefficient of electrical resistance and good metal conductivity. Tungsten carbides are formed of two types: WC and W 2 C. They differ in their behavior in acids, as well as in their solubility in other compounds with carbon.

Tungsten carbides are used to produce two types of hard alloys: sintered and cast. The latter are obtained from a powdery compound and carbide with a C deficiency (less than 3%) by casting. The second type is made from tungsten monocarbide WC and a cementing metal-bond, which can be nickel or cobalt. Sintered alloys are produced only by powder metallurgy. Cementing metal powder and tungsten carbide are mixed, pressed and sintered. Such alloys have high strength, hardness and wear resistance.

In the modern metallurgical industry, they are used for metal cutting and for the manufacture of drilling tools. One of the most common alloys are VK6 and VK8. They are used for the manufacture of cutters, cutters, drills and other cutting tools.

The field of application of tungsten carbides is quite voluminous. So, they are used to make:

• armor-piercing supplies;
• parts for engines, aircraft, spaceships and rockets;
• equipment in the nuclear industry;
• surgical instruments.

In the West, tungsten carbides are especially widely used in jewelry, especially for making wedding rings. Metal looks beautiful, aesthetically pleasing and easy to process.

This is because they are incredibly durable. It will take a lot of effort to scratch such a product. Even after a few years, the ring will look like new. It will not fade, the relief pattern will not be damaged, and the polished part will not lose its shine.

Tungsten and rhenium

The alloy of these two elements is widely used for the manufacture of high-temperature thermocouples. Tungsten - what metal? Like rhenium, it is a heat-resistant metal, and alloying elements reduces this property. But what if you take two almost identical substances? Then their melting point will not decrease.

If rhenium is used as an additive, an increase in the heat resistance and ductility of tungsten will be observed. This alloy is obtained by melting in powder metallurgy. Thermocouples made from these materials are heat resistant and can measure temperatures above 2000 ° C, but only in an inert environment. Of course, such products are expensive, because only 40 tons of rhenium and only 51 tons of tungsten are extracted in one year.

DEFINITION

Tungsten - seventy-fourth element of the Periodic Table. Designation - W from Latin "wolframium". Located in the sixth period, VIB group. Refers to metals. The nuclear charge is 74.

In terms of abundance in the earth's crust, tungsten is inferior to chromium, but exceeds molybdenum. Natural compounds of tungsten in most cases are tungstates - salts of tungstic acid H 2 WO 4. Thus, the most important tungsten ore - wolframite - consists of iron and manganese tungstates. The scheelite mineral CaWO 4 is also common.

Tungsten is a heavy white metal (Fig. 1) with a density of 19.3 g / cm 3. Its melting point (about 3400 o C) is higher than the melting point of all other metals. Tungsten can be welded and drawn into fine strands.

Figure: 1. Tungsten. Appearance.

Atomic and molecular weight of tungsten

DEFINITION

Relative molecular weight of the substance (M r) is a number showing how many times the mass of a given molecule is greater than 1/12 of the mass of a carbon atom, and relative atomic mass of an element (A r) - how many times the average mass of atoms of a chemical element is more than 1/12 of the mass of a carbon atom.

Since in the free state tungsten exists in the form of monatomic W molecules, the values \u200b\u200bof its atomic and molecular masses coincide. They are equal to 183.84.

Tungsten isotopes

It is known that in nature, tungsten can be found in the form of five stable isotopes 180 W, 182 W, 183 W, 184 W and 186 W. Their mass numbers are 180, 182, 183, 184 and 186, respectively. The nucleus of the 180 W tungsten isotope contains seventy-four protons and one hundred and six neutrons, and the rest differ from it only in the number of neutrons.

There are artificial unstable isotopes of tungsten with mass numbers from 158 to 192, as well as eleven isomeric states of nuclei.

Tungsten ions

At the outer energy level of the tungsten atom, there are six electrons, which are valence:

1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 4 6s 2.

As a result of chemical interaction, tungsten donates its valence electrons, i.e. is their donor, and turns into a positively charged ion:

W o -2e → W 2+;

W o -3e → W 3+;

W o -4e → W 4+;

W o -5e → W 5+;

W o -6e → W 6+.

Tungsten molecule and atom

In the free state, tungsten exists in the form of monatomic molecules W. Let us give some properties that characterize the atom and molecule of tungsten:

Tungsten alloys

Most of the tungsten mined is used in metallurgy for the preparation of special steels and alloys. High speed tool steel contains up to 20% tungsten and is self-hardening. Such steel does not lose its hardness even when heated to red hot.

In addition to high-speed steels, other tungsten and chromium-tungsten steels are widely used. For example, steel containing from 1 to 6% tungsten and up to 2% chromium is used for the manufacture of saws, cutters, and stamps.

As the most refractory metal, tungsten is part of a number of high-temperature alloys. In particular, its alloys with cobalt and chromium - stellites - have high hardness, wear resistance, and heat resistance. Tungsten-copper alloys combine high electrical conductivity, thermal conductivity and wear resistance. They are used for the manufacture of working parts of knife switches, switches, electrodes for spot welding.

Examples of problem solving

EXAMPLE 1

Physical properties of Tungsten.

Tungsten.

Tungsten(Wolframium) W - element of group VI, 6th period of the periodic system of D.I.Mendeleev, b. N. 74, atomic mass 183.85. Discovered in 1781 by K. Scheele. Tungsten is rarely found in nature. Forms its own minerals - wolframite and scheelite; contained as an impurity in the minerals of tin, molybdenum, titanium. Tungsten is a light gray metal, chemically resistant under normal conditions. At elevated temperatures, it reacts with oxygen, carbon and other elements. It reacts with fluorine at 20 ° C, with other halogens when heated. Acids, with the exception of hydrofluoric and nitric acids, do not affect Tungsten. In compounds, it exhibits variable valence. The most stable compounds are 6-valent tungsten. Tungsten is used for alloying steels, for the manufacture of hard alloys of filaments of electric lamps, heaters in electric furnaces, electrodes for welding, cathodes of generator lamps, high voltage rectifiers.

Tungsten crystallizes in a body-centered cubic lattice with a period a \u003d 3.1647 Å; density 19.3 g / cm3, melting point 3410 ° C, boiling point 5900 ° C. Thermal conductivity (cal / cm · sec · ° С) 0.31 (20 ° С); 0.26 (1300 ° C). Specific electrical resistance (ohm · cm · 10-6) 5.5 (20 ° С); 90.4 (2700 ° C). The work function of electrons is 7.21 · 10-19 J (4.55 eV), the radiation energy at high temperatures (W / cm2): 18.0 (1000 ° C); 64.0 (2200 ° C); 153.0 (2700 ° C); 255.0 (3030 ° C). The mechanical properties of Tungsten depend on the previous processing. Tensile strength (kgf / mm2) for sintered ingot 11, for pressure treated from 100 to 430; modulus of elasticity (kgf / mm1) 35000-38000 for wire and 39000-41000 for monocrystalline filament; Brinell hardness (kgf / mm2) for a sintered ingot 200-230, for a forged ingot 350-400 (1 kgf / mm2 \u003d 10 MN / m2). At room temperature, tungsten is low plastic.

Tungsten is chemically resistant under normal conditions. At 400-500 ° C, the compact metal is noticeably oxidized in air to WO3. Water vapor intensively oxidizes it above 600 ° C to WO3. Halogens, sulfur, carbon, silicon, boron interact with tungsten at high temperatures (fluorine with powdered tungsten - at room temperature). Tungsten does not react with hydrogen up to the melting point; with nitrogen above 1500 ° C forms nitride. Under normal conditions, tungsten is resistant to hydrochloric, sulfuric, nitric and hydrofluoric acids, as well as aqua regia; at 100 ° C weakly interacts with them; quickly dissolves in a mixture of hydrofluoric and nitric acids. In alkali solutions, when heated, tungsten dissolves slightly, and in molten alkalis, when exposed to air or in the presence of oxidizing agents, it quickly dissolves; in this case, tungstates are formed. In compounds, tungsten exhibits a valence of 2 to 6, the most stable are compounds of the highest valence.

Tungsten forms four oxides: the highest is WO3 (tungsten anhydride), the lowest is WO2, and two intermediate ones are W10O29 and W4O11. Tungsten anhydride is a lemon-yellow crystalline powder that dissolves in alkali solutions to form tungstates. When it is reduced with hydrogen, lower oxides and tungsten are sequentially formed. Tungstic anhydride corresponds to tungstic acid H2WO4 - a yellow powder, practically insoluble in water and acids. When it interacts with alkali and ammonia solutions, tungstate solutions are formed. At 188 ° C, H2WO4 eliminates water to form WO3. With chlorine, Tungsten forms a number of chlorides and oxychlorides. The most important of them: WCl6 (tp 275 ° C, tb 348 ° C) and WO2Cl2 (tp 266 ° C, sublimates above 300 ° C), are obtained by the action of chlorine on tungsten anhydride in the presence of coal. With sulfur, Tungsten forms two sulfides WS2 and WS3. Tungsten carbides WC (melting point 2900 ° C) and W2C (melting point 2750 ° C) are solid refractory compounds; obtained by the interaction of Tungsten with carbon at 1000-1500 ° C.

Light gray in color. In the periodic system of Mendeleev, he belongs to the 74th serial number. The chemical element is refractory. In its composition, it contains 5 stable isotopes.

Chemical properties of tungsten

The chemical resistance of tungsten in air and in water is quite high. It oxidizes when heated. The higher the temperature, the higher the rate of oxidation of a chemical element. At temperatures above 1000 ° C, tungsten begins to evaporate. At room temperature, hydrochloric, sulfuric, hydrofluoric and nitric acids have no effect on tungsten. A mixture of nitric and hydrofluoric acids is dissolved in tungsten. Tungsten does not mix with gold, silver, sodium, lithium neither in liquid nor in solid state. Also, there is no interaction with zinc, magnesium, calcium, mercury. Tungsten is soluble in tantalum and niobium, and with chromium and molybdenum it can form solutions in both solid and liquid states.

Application of tungsten

Tungsten is used in modern industry both in pure form and in alloys. Tungsten is a wear-resistant metal. Often alloys containing tungsten are used for the manufacture of turbine blades and aircraft engine valves. Also, this chemical element has found its application for the manufacture of various parts in X-ray engineering and radio electronics. Tungsten is used for the filaments of electric lamps.

Tungsten chemical compounds have recently found their practical application. Phosphate-tungsten heteropoly acid is used in the production of bright paints and varnishes that are resistant to light. Tungstates of rare earth elements, alkaline earth metals and cadmium are used for the manufacture of luminous paints and the manufacture of lasers.

Today, traditional gold wedding rings have begun to be replaced with products from other metals. Tungsten carbide engagement rings became popular. Such products are highly durable. The mirror polish of the ring does not fade over time. The product will keep its original condition for the entire period of use.

Tungsten is used as an alloying additive for steel. This gives the steel strength and hardness at high temperatures. Thus, tools made from tungsten steel have the ability to withstand very intense metalworking processes.